Backflow prevention assembly having a variable lay-length and orientation

ABSTRACT

A backflow prevention assembly is configurable with varying lay-lengths and orientations. The assembly includes coupling assemblies and valve bodies that adjust in length and/or rotation to allow for the varying lay-lengths and orientations of the backflow prevention valves and assemblies with and without certification. A coupling assembly is connected to a backflow prevention valve and includes an outer sleeve and an inner sleeve that is slidingly received within the outer sleeve. The lay-length is adjusted by slidably moving the inner and outer sleeves with respect to one another.

RELATED APPLICATION

The present application claims priority to and is a continuation of U.S.Non-Provisional Ser. No. 17/148,115, filed Jan. 13, 2021, entitledBackflow Prevention Assembly Having a Variable Lay-Length andOrientation (now U.S. Pat. No. 11,448,348 issued on Sep. 20, 2022),which in turn claims priority to and is a continuation of U.S.Non-Provisional Ser. No. 16/450,051, filed Jun. 24, 2019, entitledBackflow Prevention Assembly Having A Variable Lay-Length andOrientation (now U.S. Pat. No. 10,914,412 issued on Jan. 20, 2021),which in turn claims priority to and the benefit of U.S. ProvisionalPatent Application Ser. No. 62/691,037, filed Jun. 28, 2018, entitledBackflow Prevention Assembly Having A Variable Lay-Length AndOrientation, the entire contents of each is incorporated herein byreference in their entirety for all purposes.

FIELD OF THE DISCLOSURE

The subject disclosure relates to backflow prevention valves andassemblies, and more particularly to backflow prevention valves andassemblies having a variable lay-length and orientation.

BACKGROUND

In many water systems, backflow prevention valves and assemblies allowfluid and even solids to flow in a desired direction (i.e., a forwarddirection). As backsiphonage or backflow may present contamination andhealth problems, the backflow prevention valves and assemblies preventflow in an undesired direction (i.e., a backward or reverse direction).For example, backflow prevention valves and assemblies are installed inbuildings, such as residential homes, and commercial buildings andfactories, to protect public water supplies by preventing the reverseflow of water from the buildings back into the public water supply.

A typical backflow prevention assembly includes an inlet shutoff valveand an outlet shutoff valve with a backflow prevention valve extendingbetween the inlet and outlet shutoff valves. Many differentconfigurations of backflow prevention assemblies are commerciallyavailable, each being different in configuration and resultinglay-length. As used herein, “lay-length” is the distance between theends of the backflow prevention valve or, if the valve is included in anassembly, the distance between the distal ends of the shutoff valves.

The backflow prevention valve and shutoff valves of the assemblies arenormally threaded or bolted together with a fixed lay-length. As such,if a retrofit or replacement of an existing valve or assembly isdesired, spools and spacing flanges are often required to be added tothe replacement valve or assembly so that the lay-length of thereplacement valve or assembly will match the lay-length of the existingvalve or assembly in order to fit into the space left by the existingvalve or assembly in the fluid system. Such spools require advancemeasurement, planning and ordering of parts that can create delay andexpense in the retrofit process. To accommodate varying lay-lengths, thespools may be cut or manufactured to a custom length.

Additionally, backflow prevention assemblies require certification byvarious entities so that in-field reconfiguration is not possible whilemaintaining the certification. One exemplary certification organizationthat protects drinking water supplies is the Foundation forCross-Connection Control and Hydraulic Research established by theUniversity of Southern California. The approval process requires alaboratory evaluation in which the design is reviewed and then tested ina laboratory. For example, one of the important tests is the pressureloss across the backflow prevention assembly. The backflow preventionassembly must maintain pressure loss and other parameters within allowedlimits. Life cycle and back pressure tests are also required. Theapproval process also requires an extensive one-year of field evaluationin which the subject assemblies are taken apart to insure nodeformation, damage or problems occurred that could cause poorperformance. Every three years, the certification for the backflowprevention assembly must be renewed. As such, one cannot simplydisassemble and reconfigure a backflow prevention assembly in the fieldwithout voiding its certification.

SUMMARY

The present disclosure provides a new and improved backflow preventionvalve and assembly having a variable lay-length that quickly and easilyadjusts to the fluid system for easy retrofit and installation withoutneed of a custom fit, fixed-length spool. The new and improved backflowprevention valve and assembly and associated variable-length couplingassemblies can be pre-certified by the manufacturer for adjustment ofthe lay-length during installations in the field in retrofitapplications. Thus, in-field adjustments to lay-length may be madewithout additional parts while maintaining certification.

Among other aspects and advantages, the new and improved backflowprevention valve and assembly of the present disclosure can accommodateself-adjustment while in service. For example, thermal expansion,seismic activity, movement related to thermal cycles like freezing andthe like may create expansion and contraction forces on the backflowprevention valve and assembly which the variable lay-length absorbs bythe inherent ability to freely lengthen and shorten.

According to one aspect of the present disclosure, the variablelay-length is obtained using coupling assemblies that can vary inlongitudinal length. According to another aspect, the variablelay-length is obtained using a valve housing that can vary inlongitudinal length.

According to a further aspect of the present disclosure, the variablelength coupling and the variable length valve housing are also rotatableabout a longitudinal axis. The rotation allows for an orientation of thebackflow prevention valve and assembly of the present disclosure to bevaried, accommodates easier installation during retrofit applications,and permits more self-adjustment while in service.

According to a further aspect of the present disclosure, there is abackflow prevention assembly, comprising: a first shutoff valve; asecond shutoff valve; an outer sleeve connected to one of the first andsecond shutoff valves; an inner sleeve connected to the other of thefirst and second shutoff valves and slidingly received within the outersleeve such that a lay-length of the backflow prevention assembly can bevaried; a fluid seal positioned between the inner sleeve and the outersleeve; and a check valve, connected to the inner sleeve, configured toallow fluid flow through the backflow prevention assembly in a singledirection.

According to a further aspect of the present disclosure, there is abackflow prevention assembly, comprising: a first shutoff valve; asecond shutoff valve; a first backflow prevention valve connectedbetween the first and second shutoff valves; and a coupling assemblyconnected to at least one of the first backflow prevention valve, thefirst shutoff valve and the second shutoff valve, wherein the couplingassembly, the first backflow prevention valve and the first and secondshutoff valves define a lay-length of the backflow prevention assembly.The coupling assembly includes: a first end; a second end; an outersleeve extending from the first end; an inner sleeve extending from thesecond end and slidingly received within the outer sleeve such that adistance between the first and second ends of the coupling assembly canbe varied to adjust the lay-length of the backflow prevention assembly;and a fluid seal positioned between the inner sleeve and the outersleeve.

According to a further aspect of the present disclosure, there is abackflow prevention assembly having a variable lay-length, comprising: afirst shutoff valve; a second shutoff valve; a first backflow preventionvalve connected between the first shutoff valve and the second shutoffvalve; and a coupling assembly, connected to at least one of the firstbackflow prevention valve. The first shutoff valve or the second shutoffvalve, includes: a first end; a second end; an outer sleeve extendingfrom the first end; an inner sleeve extending from the second end andslidingly received within the outer sleeve; and a fluid seal positionedbetween the inner sleeve and the outer sleeve, wherein the lay-length isvaried by sliding the inner and outer sleeves with respect to oneanother along a common axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the disclosure are discussed herein with reference tothe accompanying Figures. It will be appreciated that for simplicity andclarity of illustration, elements shown in the drawings have notnecessarily been drawn accurately or to scale. For example, thedimensions of some of the elements may be exaggerated relative to otherelements for clarity or several physical components may be included inone functional block or element. Further, where considered appropriate,reference numerals may be repeated among the drawings to indicatecorresponding or analogous elements. For purposes of clarity, however,not every component may be labeled in every drawing. The Figures areprovided for the purposes of illustration and explanation and are notintended as a definition of the limits of the disclosure. In theFigures:

FIG. 1 a illustrates a first configuration of an exemplary embodiment ofa backflow prevention assembly in accordance with the subjectdisclosure;

FIG. 1 b illustrates another configuration of the backflow preventionassembly of FIG. 1 a;

FIG. 1 c illustrates still another configuration of the backflowprevention assembly of FIG. 1 a;

FIG. 1 d ′illustrates still another configuration of the backflowprevention assembly of FIG. 1 a;

FIG. 1 e is an exploded view of an exemplary embodiment of a backflowprevention valve for use in the assembly shown in FIGS. 1 a through 1 d;

FIG. 2 illustrates an exemplary embodiment of a coupling in accordancewith the subject technology for use in the assembly shown in FIGS. 1 athrough 1 d;

FIG. 3 a illustrates a sectional view of the coupling taken along line3-3 of FIG. 2 ;

FIG. 3 b illustrates a sectional view of another exemplary embodiment ofa coupling in accordance with the subject technology for use in theassembly shown in FIGS. 1 a through 1 d;

FIG. 4 illustrates a partial cross-sectional view of an exemplaryembodiment of a coupling in accordance with the subject technology foruse in the assembly shown in FIGS. 1 a through 1 d;

FIG. 5 illustrates a partial cross-sectional view of another exemplaryembodiment of a coupling in accordance with the subject technology foruse in the assembly shown in FIGS. 1 a through 1 d;

FIG. 6 illustrates a partial cross-sectional view of still anotherexemplary embodiment of a coupling in accordance with the subjecttechnology for use in the assembly shown in FIGS. 1 a through 1 d;

FIG. 7 illustrates another exemplary embodiment of backflow preventionassembly in accordance with the subject disclosure;

FIG. 8 illustrates a further exemplary embodiment of a backflowprevention assembly in accordance with the subject disclosure;

FIG. 9 illustrates a cross-sectional view of an exemplary embodiment ofa coupling in accordance with the subject technology for use in theassemblies shown in FIGS. 7 and 8 :

FIG. 10 illustrates a cross-sectional view of another exemplaryembodiment of a coupling in accordance with the subject technology foruse in the assemblies shown in FIGS. 7 and 8 ;

FIG. 11 illustrates an additional exemplary embodiment of a backflowprevention assembly in accordance with the subject disclosure; and

FIG. 12 illustrates an additional exemplary embodiment of a backflowprevention assembly in accordance with the subject disclosure.

DETAILED DESCRIPTION

The subject technology overcomes many of the prior art problemsassociated with backflow prevention assemblies. The advantages, andother features of the technology disclosed herein, will become morereadily apparent to those having ordinary skill in the art from thefollowing detailed description of certain exemplary embodiments taken incombination with the drawings and wherein like reference numeralsidentify similar structural elements. It should be noted thatdirectional indications such as vertical, horizontal, upward, downward,right, left and the like, are used with respect to the figures and notmeant in a limiting manner.

In brief, the subject technology is directed to backflow preventionvalves and assemblies that have varying lay-lengths and orientations andmay include coupling assemblies and valve bodies that adjust in lengthand/or rotation to allow the varying lay-lengths and orientations of thebackflow prevention valves and assemblies with and withoutcertification.

Referring now to FIG. 1 a , there is shown a backflow preventionassembly 10 in accordance with the subject technology. The backflowprevention assembly 10 is installed in a fluid system 20 (e.g., a watersupply for a building mounted at a location in the ground 23). The fluidsystem 20 includes fluid conduits that carry fluid in a forwarddirection (e.g., left to right in FIG. 1 a ) with the backflowprevention assembly 10 preventing flow in the backward direction (e.g.,right to left in FIG. 1 a ). The fluid system 20 will include strainers,meters and other typical components that are not shown in FIG. 1 a . Thefluid system 20 has pipes 22 that terminate in opposing ends fitted withmounting flanges 24 a, 24 b. Typically, the distance between themounting flanges 24 a, 24 b is fixed so that when installing thebackflow prevention assembly 10, a lay-length 18 of the backflowprevention assembly 10 should be matched to the distance between themounting flanges 24 a, 24 b. The backflow prevention assembly 10 may bemounted horizontally or vertically as well as in parallel with anothercomponent such as even another backflow prevention assembly.

The backflow prevention assembly 10 can be modular and may includeidentical or functionally similar components so that some components maybe interchanged. The backflow prevention assembly 10 includes an inletshutoff valve 12 a and an outlet shutoff valve 12 b. Each shutoff valve12 a, 12 b couples to a respective flange 24 a, 24 b of the fluid system20. The shutoff valves 12 a, 12 b may be interchangeable. The backflowprevention assembly 10 also includes two backflow prevention valves 14a, 14 b, also referred to as “check valves,” connected to a respectiveshutoff valve 12 a, 12 b. The two backflow prevention valves 14 a, 14 bmay be interchangeable.

An exemplary embodiment of a backflow prevention valve 14 x, as known toone of ordinary skill in the art, is shown, in an exploded view, in FIG.1 e . Accordingly, a check valve assembly 50 includes a seat O-ring 52,a seat 54, a disk and spring assembly 56, a cover O-ring 58 and a cover60. The seat O-ring 52 and the cover O-ring 58 provide a fluid seal.

Owing to the fact that a backflow prevention assembly is critical forwater safety, it is tested, for example, annually, to assure that it isin proper operating condition. Specifically, as is known, fluid pressuremeasurements are taken at specified locations in the backflow preventionassembly 10. To facilitate these pressure measurements, the backflowprevention assembly 10 includes a number of test cocks 30, each of whichincludes a ball valve, and which is threadably connected to couple witha fluid path within the backflow prevention assembly 10 via acorresponding test cock port (not shown).

In a known implementation, four test cocks are located on the backflowprevention assembly 10 in order to allow for temporarily attachingmeasuring equipment to measure the flow to ensure that the backflowprevention assembly 10 is functioning correctly. Thus, for example, atest cock may be provided to measure the pressure coming into thebackflow prevention assembly 10; another test cock measures the pressurejust before a first check valve; a third test cock measures the pressureright after the first check valve; and a fourth test cock measures thepressure right after a second check valve.

While not all test cocks 30 are shown in the Figures, a test cock 30 ais shown as provided on the backflow prevention valve 14 a and a testcock 30 b is provided on the backflow prevention valve 14 b. One ofordinary skill in the art will understand where other test cocks areplaced in order to provide for a testable backflow prevention assembly10.

In the exemplary embodiment of the assembly 10 shown in FIG. 1 a , avariable length coupling assembly 100 extends between the two checkvalves 14 a, 14 b. The variable length of the coupling assembly 100allows the overall lay-length 18 of the backflow prevention assembly 10to be adjusted to match the fixed distance between the mounting flanges24 a, 24 b for easy and quick installation. In the exemplary embodimentshown, the coupling assembly 100 also is rotatable about its length toallow for efficient alignment of the components.

The backflow prevention assembly 10 being modular allows for severalvarying configurations. In FIG. 1 b , for example, the coupling assembly100 extends between the inlet shutoff valve 12 a and the check valve 14a. Similarly, the coupling assembly 100 could be located between thecheck valve 14 b and the outlet shutoff valve 12 b. For another exampleshown in FIG. 1 c , the coupling assembly 100 extends from the outletshutoff valve 12 b for connection to the mounting flange 24 b to act asan adjustable coupling. Alternatively, the coupling assembly 100 couldextend from the inlet shutoff valve 12 a for connection to the mountingflange 24 a.

For another example, as shown in FIG. 1 d , the coupling assembly 100can be provided to extend vertically, with respect to the ground 23,between the input and its respective shutoff valve 12 a and the outputand its respective shutoff valve 12 b. In addition, the couplingassembly 100 can be vertically placed between the shutoff valve 12 a andthe check valve 14 a and between the shutoff valve 12 b and the checkvalve 14 b. Further, and similar to the configuration in FIG. 1 a , thecoupling assembly 100 can be placed horizontally between the check valve14 a and the check valve 14 b. It should be noted that while twovertically-oriented sections are shown in FIG. 1 d with the couplingassemblies 100, one of ordinary skill in the art will understand that itis not necessary that both be constructed as such and the claims are notintended to be limited to the embodiment shown in FIG. 1 d.

An exemplary embodiment of the coupling assembly 100 is shown in FIGS. 2and 3 a. The coupling includes first and second ends 102, 104, an outersleeve 110 extending from the first end 102, and an inner sleeve 120extending from the second end and slidingly received within the outersleeve such that a length 140 between the first and the second ends 102,104 of the coupling assembly 100 can be varied to vary the lay-length 18of the backflow prevention assembly 10 of FIGS. 1 a through 1 d . Theouter sleeve 110 has an open distal end 112 receiving an open distal end122 of the inner sleeve. A fluid seal 130 is positioned between theinner sleeve 120 and the outer sleeve 110 to provide a fluid-tight sealbetween the sleeves, yet allow sliding movement between sleeves. Thefluid seal may comprise, for example, an O-ring 130. As discussed below,the present disclosure also includes the addition of one or moresprings, or another type of biasing feature, in the coupling assembly100 to cause the sleeves to be biased, or urged, away from one anotheralong their common axis.

As shown in FIG. 3 a , the sleeves 110, 120 have circular cross-sectionsso that the sleeves can rotate with respect to each other about alongitudinal axis 150 of the coupling assembly 100. In alternativeembodiments, the sleeves may have non-circular cross-sections to preventrotation with respect to one another. For example, in FIG. 3 b thecoupling assembly 100 is shown with an outer sleeve 110 a and an innersleeve 120 a each having an oval-shaped cross-section that preventrotation with respect to each other.

In the exemplary embodiment of FIGS. 2 through 3 b, the ends 102, 104 ofthe coupling assembly 100 comprise flanges for connection to the othercomponents of the backflow prevention assembly 10 and/or the mountingflanges 24 a, 24 b of the fluid system 20. It should be noted, however,that the ends could take other forms to facilitate connection of thecoupling assembly 100 to the backflow prevention assembly 10 and/or thefluid system 20. In addition, it should be understood that one or bothof the ends 102, 104 of the coupling assembly 100 could be unitarilyformed with the check valves 14 a, 14 b and/or the shutoff valves 12 a,12 b. For example, the first end 102 and the outer sleeve 110 could beunitarily formed with the check valve 14 a, and the second end 104 andthe inner sleeve 120 could be unitarily formed with the check valve 14b.

Referring now to FIG. 4 , a partial cross-sectional view of an exemplaryembodiment of a coupling assembly 100 a in accordance with the subjecttechnology is shown. The coupling assembly 100 a is similar to thecoupling assembly 100 of FIGS. 2 and 3 a, but includes a snap ring 160received in a radially inwardly facing groove 114 of the outer sleeve110. The inner sleeve 120 includes a flange 124 at its distal end 122that, in combination with the snap ring 160, holds the inner sleeve 120within the outer sleeve 110. As discussed below, the present disclosurealso includes the addition of one or more springs, or another type ofbiasing feature, in the coupling assembly 100 a to cause the sleeves tobe, or urged, away from one another along their common axis.

Referring now to FIG. 5 , a partial cross-sectional view of anothercoupling assembly 100 b in accordance with the subject technology isshown. The coupling assembly 100 b is similar to the coupling assembly100 of FIGS. 2 and 3 a, but includes a groove 211 in the flange 102 forreceiving an O-ring 213 to provide a fluid tight seal to the flange1102. The coupling flange 102 and fluid system flange 24 a may betightly held together by one or more retaining clips 215 that snap ontothe flanges 24 a, 102. The inner sleeve 120 includes two radiallyoutwardly facing annular channels 217 for retaining respective O-rings219 to insure fluid tight sealing between the sleeves 120, 110. In thisembodiment of the coupling assembly 100 b, the sleeves 120, 110 arerotatable and slidable but a retention feature is not needed because thebackflow prevention assembly 100 maximum installed length will not allowfor the sleeves 120, 110 to be disengaged from one another. In analternate approach, as would be understood by one of ordinary skill inthe art, a clamp ring can be used in place of the retaining clip 215.

Referring now to FIG. 6 , a partial cross-sectional view of anothercoupling assembly 100 c in accordance with the subject technology isshown. The coupling assembly 100 c is similar to the coupling assembly100 of FIGS. 2 and 3 a, but the outer sleeve 110 includes a narrowedinner diameter that forms a minimum lay-length travel stop 321 for theinner sleeve 120. The flange 102 of the coupling assembly 100 c issecured to the flange 24 b using a threaded union nut 323.

Referring now to FIGS. 7 and 8 , additional embodiments of certifiedbackflow prevention assemblies 40 a, 40 b, are shown, each having one ormore variable length and/or rotatable coupling assembly 500 inaccordance with the subject disclosure. Each coupling assembly 500 ofFIGS. 7 and 8 is generally similar to the coupling assembly 100 of FIGS.1 a through 1 d . Each of the backflow assemblies 40 a, 40 b includes abackflow prevention valve 44, a first shut-off valve 42 a, and a secondshut-off valve 42 b. As can be seen from FIG. 8 , an overall height 49of the backflow prevention assembly 40 b can be changed by adjusting thelength of the coupling assemblies 500 a, 500 d. A lay-length 48 of theassembly can be changed by adjusting the length of one or both of thecoupling assemblies 500 b, 500 c. In addition, the orientation of theassembly 40 b can be varied such that the shut-off valves 42 a, 44 bpoint in different directions by rotating one or both of the couplingassemblies 500 b, 500 c. For example, as shown in FIG. 8 both shut-offvalves 42 a, 44 b point downward. However, the coupling assembly 500 ccould be rotated so that the second shut-off valve 44 b points upward.

In addition, similar to the backflow prevention assembly 10 of FIGS. 1a-1 d , a number of test cocks 30-1-30-4 are provided in order tomeasure the operating condition of the backflow prevention assemblies 40a, 40 b.

Referring now to FIG. 9 , a partial cross-sectional view of an exemplaryembodiment of a coupling assembly 500 in accordance with the subjecttechnology is shown. The coupling assembly 500 is similar to thecoupling assembly 100 of FIGS. 2 and 3 a, and similar elements areindicated with like reference numbers in the “500” series instead of the“100” series. The coupling assembly 500 incorporates a press fittingseal ring 511 in an outer sleeve 510 that retains an O-ring 530. In oneapproach, the coupling assembly 500 is installed without crimping theseal ring 511. The O-ring 530 still will provide a fluid tight seal, butthe sleeves 510, 520 will be allowed to slide and rotate and a length540 will remain variable so that subsequent expansion and contraction ispossible post-installation.

Alternatively, the press fitting seal ring 511 can be crimped to fix thelength 540 (and rotation) of the coupling assembly 500. In the exemplaryembodiment shown, a second end 504 of the coupling assembly 500 issecured to the shut-off valve 42 a with solder 560, and the first end502 of the coupling assembly 500 includes a threaded union nut 562 forconnecting the coupling assembly 500 to the backflow prevention valve44.

Referring now to FIG. 10 , a cross-sectional view of another exemplaryembodiment of a coupling assembly 600 in accordance with the subjecttechnology is shown. The coupling assembly 600 is similar to thecoupling assembly 100 of FIGS. 2 and 3 a, and similar elements areindicated with like reference numbers in the “600” series instead of the“100” series. The coupling assembly 600 incorporates a quick connectfitting for coupling sleeves 610, 620 together.

In one approach, the quick connect fitting is a push-to-connect fitting670 so that soldering, crimping or joining materials are not required.The push-to-connect fitting 670 includes a collet 672, a cap 674, anO-ring guide 676, and a clip 678 for locking the fitting. For assembly,it is only required to push the inner sleeve 620 into the outer sleeve610. Removing the clip 678 and pushing in the collet 672 allows thesleeve 620 to be removed. Examples of push-to-connect fittings and pressfittings that can be incorporated into the subject technology can befound at www.watts.com.

Referring now to FIG. 11 , another exemplary embodiment of a backflowprevention assembly 1010 is shown. The assembly 1010 includes a backflowprevention valve 1100 having an inner sleeve 1120 containing a firstcheck valve 1500 and a second check valve 1600. The inner sleeve 1120 isslidingly received within an outer sleeve 1110 such that a lay-length1140 of the assembly 1010 can be varied. O-rings 1130 provide a sealbetween the sleeves 1110, 1120 yet allow the inner sleeve 1120 to slidewithin the outer sleeve 1110. The sleeves 1110, 1120 may be providedwith circular cross-sections so that the sleeves 1110, 1120 can rotatewith respect to each other about a longitudinal axis 1150 of theassembly 1010. In alternative embodiments, the sleeves may havenon-circular cross-sections to prevent such relative rotation.

The valve 1100 can include a feature for biasing the sleeves 1110, 1120away from one another along the longitudinal axis 1150. In the exemplaryembodiment, the biasing feature includes compression springs 1108 (shownschematically) positioned between the sleeves 1110, 1120. This springs1108 may be separate from both of the sleeves 1110, 1120 or one end of aspring may be attached to one or the other of the sleeves 1110, 1120.

While a coil, or helical, spring 1108 is shown, other components orstructures that store mechanical energy can be used, for example, butnot limited to, a leaf spring or a cantilever spring. Further, thebiasing feature may have a constant force, i.e., a forceful resistancethat remains the same during a deflection cycle or a variable force,i.e., a force or resistance that varies as it is compressed.

In the exemplary embodiment shown in FIG. 11 , the backflow preventionassembly 1010 includes a first coupling sleeve 1200 slidingly receivinga first end 1102 of the valve 1100 and a second coupling sleeve 1300slidingly receiving a second end 1104 of the valve 1100. The couplingsleeves 1200, 1300 allow the lay-length 1140 the backflow preventionassembly 1010 to be further expanded. The sleeves 1110, 1120, 1200, 1300may be provided with circular cross-sections so that the sleeves canrotate with respect to each other about the longitudinal axis 1150 ofthe backflow prevention assembly 1010. In alternative embodiments, oneor more of the sleeves 1110, 1120, 1200, 1300 may have non-circularcross-sections to prevent such relative rotation.

Although not shown, the backflow prevention assembly 1010 may furtherinclude a feature for fixing, or locking, one or more of the sleeves1110, 1120, 1200, 1300 in position after installation of the backflowprevention assembly 1010 in a fluid system. For example, the backflowprevention assembly 1010 could include bolts for securing the firstcoupling sleeve 1200 to the outer sleeve 1110 to prevent sliding orrotation between the sleeves 1200, 1110 after installation of thebackflow prevention assembly 1010.

In the exemplary embodiment shown in FIG. 11 , the backflow preventionassembly 1010 includes test cock valves 1400 (shown schematically). Thetest cock valves 1400 are for use to facilitate testing of the backflowprevention assembly 1010. During testing procedures, pressure gauges(not shown) are connected to the test cock valves 1300 and the test cockvalves are opened. Backflow assemblies with test cock valves arecurrently designated as “testable.”

Another exemplary embodiment of a backflow prevention assembly is shownin FIG. 12 . The backflow prevention assembly 2000 is a variation of theassembly 1010 and has the same arrangements of components as theassembly 1010 except for the feature for biasing the sleeves 1110, 1120away from one another along the longitudinal axis 1150. Instead of twosprings 1108, the assembly 2000 includes a single spring 2108 that issized to slidably fit within the outer sleeve 1110 to exert a forceagainst the inner sleeve 1120 such that a lay-length 1140 of theassembly 2000 can be varied. Alternatively, the single spring 2108 canbe replaced by two or more springs as would be understood by one ofordinary skill in the art. The assembly 2000 otherwise operates in thesame manner as the assembly 1010.

The variable lay-length 1140 of the backflow prevention assembly 1010expedites service (especially for those backflow assemblies currentlydesignated as “testable”) or replacement operations (especially forthose backflow assemblies currently designated as “untestable”). Bylocking the backflow prevention assembly 1010 in an expanded positionafter installation (larger than that of the open pipe section, but lessthan that which would restrict movement at one or both ends of theassembly 1010) the backflow prevention assembly 1010 is allowed tofloat, or vary by length, along the longitudinal axis 1150 and betweenthe fixed ends of a fluid system. If the sleeves 1110, 1120, 1200, 1300include circular cross-sections, the backflow prevention assembly 1010or parts thereof may be allowed to be rotated about the longitudinalaxis 1150 between the fixed ends of a fluid system.

To perform service or replacement, one need only to push the two centralsleeves 1110, 1120 together against the force of the springs 1108,allowing the valve 1100 to be removed from the coupling sleeves 1200,1300. Once removed, the sleeves 1110, 11120 can be disassembled and thecheck valves 1500, 1600 removed for inspection, repair or replacement asdesired. Reversing the removal steps returns the backflow preventionassembly 1010 to normal operating conditions.

In another aspect of the present disclosure, any of the foregoingassemblies can include a reduced pressure zone assembly, for example,the Series 880V MasterSeries Configurable Design Reduced Pressure ZoneAssembly from Watts, provided between the check valves.

Backflow prevention valves and assemblies need to be certified by aqualified certifying agency in order to comply with various regulations.Such certifying agencies can include the Foundation for Cross-ConnectionControl and Hydraulic Research (FCCCHR), American Society of SanitaryEngineers (ASSE), The American Water Works Association (AVVWA), TheInternational Association of Plumbing and Mechanical Officials (IAPMO),Underwriters Laboratories (UL), and Canadian Standards Association (GSA)International, for example. The backflow prevention assemblies disclosedherein can be certified from shut-off valve to shut-off valve from theplace of manufacture before they are installed in replacement sites. Thecertifications allow the lay-length and orientation of the assemblies tobe varied by installers in the field such that the assemblies can beinstalled in replacement of existing assemblies that may have had adifferent lay-length.

The subject components may be fabricated from any suitable material orcombination of materials such as lightweight stainless steel, epoxycoated carbon steel, zinc plated carbon steel, copper, copper alloys,suitable plastics and composites, and the like.

It will be appreciated by those of ordinary skill in the pertinent artthat the functions of several elements may, in alternative embodiments,be carried out by fewer elements, or a single element. Similarly, insome embodiments, any functional element may perform fewer, ordifferent, operations than those described with respect to theillustrated embodiment. Also, functional elements (e.g., check valves,shut-off valves, and the like) shown as distinct for purposes ofillustration may be incorporated within other functional elements in aparticular implementation.

While the subject technology has been described with respect to variousembodiments, those skilled in the art will readily appreciate thatvarious changes and/or modifications can be made to the subjecttechnology without departing from the scope of the present disclosure.

What is claimed is: 1-32. (canceled)
 33. A backflow prevention assembly,comprising: a first shutoff valve; a second shutoff valve; an outersleeve connected to one of the first and second shutoff valves, theouter sleeve having a first axis; an inner sleeve connected to the otherof the first and second shutoff valves, wherein the inner sleeve iscoupled to the outer sleeve for rotation with respect to the first axisand for sliding along the first axis such that a rotational orientationand a lay-length of the bald low prevention assembly can be varied andset to a desired rotational orientation and lay-length; and a checkvalve, connected to the outer sleeve, configured to allow fluid flow ina single direction.
 34. The backflow prevention assembly as recited inclaim 33, wherein the inner sleeve has an outer diameter sized to fitwithin the outer sleeve for rotation about the first axis.
 35. Thebackflow prevention assembly as recited in claim 34, wherein the outersleeve has an inner diameter.
 36. The backflow prevention assembly asrecited in claim 35, wherein a portion of the inner diameter of theouter sleeve has a narrowed inner diameter that forms a minimumlay-length travel stop.
 37. The backflow prevention assembly as recitedin claim 33, wherein the backflow prevention assembly retainscertification thereof from a qualified certifying agency for anylay-length and rotational orientation of the inner sleeve positionedwith respect to the outer sleeve.
 38. The backflow prevention assemblyas recited in claim 33, further comprising a spring configured to biasthe inner and outer sleeves away from one another along a common axis tothe sleeves.
 39. A backflow prevention assembly for installation into afluid system, the backflow prevention assembly comprising: a firstshutoff valve disposed in proximity to an inlet of the fluid system; asecond shutoff valve disposed in proximity to an outlet of the fluidsystem outlet; a check valve disposed between the first shut off valveand the second shutoff valve; and a coupling assembly disposed betweenor outside of the first and second shutoff valves, the coupling assemblyhaving: an outer sleeve; and a complimentary inner sleeve coupled to aninterior of the outer sleeve, the inner sleeve extendable relative tothe outer sleeve.
 40. A backflow prevention assembly comprising: a firstshutoff valve; an elongated outer sleeve extending along a first axisand connected to the first shutoff valve; an inner sleeve coupled to theelongated outer sleeve for at least one of: rotating with respect to thefirst axis to selectively vary at least one of a rotational orientationof the backflow prevention assembly; and sliding along the first axis toselectively vary a lay-length of the backflow prevention assembly. 41.The backflow prevention assembly as recited in claim 34, furthercomprising a second shutoff valve, wherein the inner sleeve is connectedto the second shutoff valve.
 42. The backflow prevention assembly asrecited in claim 34, further comprising a fluid seal between the innersleeve and the elongated outer sleeve.
 43. The backflow preventionassembly as recited in claim 34, further comprising a check valve,connected to the elongated outer sleeve, configured to allow fluid flowin a single direction.